Analysis Of Optimal Nutritional Requirements And Optimization Of Culture Conditions For Lactobacillus Helveticus H11

High density culture process is the basis for industrial application of lactic acid bacteria.The Lactobacillus helveticus H11 selected in this study has excellent probiotic properties such as antihypertensive,antibacterial and immunomodulatory,but there are problems such as low biomass,low bacterial population and weak activity in its culture process.The aim of this study was to analyze the optimal nutritional requirements of Lactobacillus helveticus H11 and to optimize its culture conditions in order to improve the biomass,bacterial density and activity of the bacterium,and the following conclusions were reached:（1）Determine the static fermentation medium formulation of Lactobacillus helveticus H11.The optimal static fermentation medium formulation for Lactobacillus helveticus H11 was optimized by response surface test design and single factor test as follows:Lactose 29.70 g/L,Yeast extract FM808 41.78 g/L,Yeast peptone FP102 13.93 g/L,Sodium citrate 2.02 g/L,Sodium acetate 5.05 g/L,K₂HPO₄ 2.02 g/L,Mg SO₄·7H₂O 0.20g/L,Mn SO₄·5H₂O 0.06 g/L,Tween-80 1.00 g/L,L-cysteine hydrochloride 0.30 g/L,VB60.01 g/L.（2）Determination of static fermentation culture conditions of Lactobacillus helveticus H11.The optimized medium was used to optimize the optimal static fermentation conditions,and the optimal static culture conditions for Lactobacillus helveticus H11 were finally determined to be 37℃,2%inoculum,initial pH 6.5,and the static culture viable bacteria count was（3.62±0.15）×10⁹ CFU/m L,which was 11.24 times higher than that of MRS medium（2.90±0.08）×10⁸ CFU/m L.11.24 times.（3）To determine the high-density culture process of Lactobacillus helveticus H11.The optimal high-density culture method was obtained as follows:incubation temperature37℃,carbon source three times the amount of static fermentation medium,initial pH 6.5,constant pH 5.9,holding gas is nitrogen,stirring speed 200 r/min in a bioreactors,and the optimized Lactobacillus helveticus H11 had significantly higher density,more vigorous growth rate and longer logarithmic growth period.The optimized Lactobacillus helveticus H11 had significantly higher density,more vigorous growth rate and longer logarithmic growth period.The viable count of Lactobacillus helveticus H11 fermentation broth was（9.02±0.23）×10⁹ CFU/m L,which was 2.5 times higher than that of the static culture（3.62±0.15）×10⁹ CFU/m L.By analyzing the optimal nutritional requirements of Lactobacillus helveticus H11and optimizing the culture conditions,this study determined the optimal fermentation process for the industrial production of Lactobacillus helveticus H11,which increased its viable bacteria count and reduced the production cost,and provided a theoretical basis for the industrial production of Lactobacillus helveticus H11.